EFFECTS OF OIL DEGRADATION ON THE FRICTION AND WEAR PROPERTIES OF SILICON NITRIDE/M-50 STEEL SLIDING COUPLES

摘要

The effect of oil degradation on the wear behavior of the silicon nitride/M50 steel system has been studied in order to understand the influences of oil degradation on bearing performance. Degraded oil samples were generated by heating a conventional gas turbine lubricant (MIL-L-23699) to temperatures between 200-300 deg C for various times. Sample characterization was performed using total acid number, antioxidant concentration, rheometry, surface tension, spectroscopy, and gel permeation chromatography. Coefficient of friction and rate of wear were measured on the oil samples using a pin-on-disk test apparatus under a Hertzian contact stress of 1.6 GPa at 25 + -1 deg C. Results show significant physical and chemical changes which could not be attributed to any specific degradation product. Degradation is shown to increase the coefficient of friction, with no correlations to wear measurements.